1. Field of the Invention
This invention pertains to the thermal hydrogenation of coal to produce principally fuel gas product. It pertains more particularly to an integrated coal hydrogenation process without added catalyst for producing C.sub.1 -C.sub.3 boiling range fuel gases, wherein essentially all the C.sub.4 -400.degree. F. light liquid fractions produced are steam reformed to make the needed hydrogen, and the heavier 400.degree.-975.degree. F. liquid fractions are used as fuel for the reformer and other process needs.
2. Description of Prior Art
It has been determined that one of the most costly factors in the thermal hydrogenation of solid coal with the objective of mainly producing normally gasiform hydrocarbons is the cost of hydrogen. Consumption of hydrogen varies somewhat with the rank of the coal, but usually amounts to from 10 to 20 standard cubic feet (SCF) per pound of coal feed. There must be a source of relatively high purity hydrogen readily available to the hydrogenation reactor, and supplying the required hydrogen has posed a problem. An economic and technically advanced process for production of hydrogen is that of steam reforming of low boiling hydrocarbon liquids, and a coal hydrogenation process producing mainly fuel gas product while also supplying these constituents in sufficient quantity from the coal for making needed hydrogen would provide important economic advantages.
While the hydrogenation of coal without added catalyst to produce gaseous and liquid products is known, having been disclosed in U.S. Pat. No. 3,617,465 to Wolk et al., such processes have produced principally coal-derived liquids along with only incidental amounts of gas. Also, such processes have used externally produced hydrogen for make-up requirements and have not provided internally a convenient source of the needed make-up hydrogen of desired or optimum purity, while also producing principally a fuel gas product having high heating value.